Tate Modern

Industrial light and magic

Tate Modern was meant to make us look at contemporary art in a new way, but its most immediate cultural impact will be on how we see architecture. Herzog and de Meuron have turned a power station of no architectural pretension into a museum that is spectacular enough to be an authentic crowd-pleaser. But at the same time, it will satisfy the most austere artists, wary of being exhibited in galleries in which the architectural ego is too conspicuously on display.

Bankside is a defining moment for architecture. Just like Piano and Rogers's Pompidou Centre in the Seventies and James Stirling's Staatsgalerie in the Eighties, it will be the benchmark for gallery architecture for a decade. And that, of course, was by no means an accident. Nicholas Serota is a gallery director with an unusually sophisticated view of architecture and the contribution it can make to a successful museum. He wanted a building that artists would like, but he also wanted a building which would set the architectural agenda, because he knew that if it did both, it would also be popular with the public.

The trick was to pick an architect at just the right moment in their career. They should have done just enough other work to prove that they are capable of handling larger projects, but they should not yet have done that other big project which marks them out as somebody else's discovery or, worse, makes them too busy to concentrate. And it was at exactly this point that Serota found Herzog and de Meuron. Such architects are not exactly in over-abundant supply. It is interesting that the only really tense moment in Serota's six-year relationship with his architects was when Herzog and de Meuron got on to the Museum of Modern Art's shortlist to design an extension in New York.

There are other art galleries that have been carved out of industrial spaces, but they were mainly on the edge of things. The Tate, on the other hand, is at the centre of them, a major national institution that has adopted the same architectural language as what was once regarded as the radical fringe. Tate Modern is a monumental version of Matt's Gallery, the ramshackle collection of sheds in the East End that first showed Richard Wilson, or the Saatchi Gallery. Suddenly, the tidied-up industrial space has become as much the conventional gallery form as the Greek temple used to be. The people who put up those brown, motorway heritage signs will have to rethink the stylised representation of the pediment and columns they use to warn us that there is a museum ahead. The conventional sign for a gallery is now Tate Modern's chimney.

But the Bankside effect will go wider than just the art world. Herzog and de Meuron have demonstrated that austere, serious-minded, grown-up architecture, designed by architects who are neither apologetic about their work, nor who feel the need to ingratiate themselves with their audience, can have real popular appeal.

What makes Tate Modern work is that its architects have had the confidence to do a few, very simple things brilliantly well. The light in the galleries is beautiful. The turbine hall, its proportions intensified by excavating the floor down into what was the basement, is truly heroic. And for what is fundamentally a Swiss building, the timber floors, the expanses of unpretentious concrete, and the bricks make it surprisingly tactile. This kind of thing is much more difficult to do than it looks, as other museums that have struggled to tame relics of the industrial revolution no less imposing than Bankside have discovered. In Madrid, the Reina Sofia, which now holds Picasso's Guernica , has still not managed to shake off the grey, institutional feel of the original hospital. And Gae Aulenti's Busby Berkeley insertions in the Gare d'Orsay crush the impressionists into visual insignificance.

Herzog and de Meuron have accepted the logic of the building, with its sparse finishes and made it into something it never was - a public building. A new entrance has been pierced in the west wall and the old machine hall is set to become London's indoor version of the square in front of the Pompidou. 'We don't want to shock people, or overwhelm them,' says Jacques Herzog. 'You accept the existing building as an artificial landscape. Why should you demolish a mountain? Our strategy was to make it a public building.'

Bankside also represents a significant shift in the way that architects deal with old buildings. The conventional approach has been deliberately to play up the tension between new and old, to contrast mellow brick with glittering, hi-tech insertions that look like jewellery. Herzog and de Meuron don't buy that. They aren't interested in the archaeology of Gilbert Scott's flimsy brickwork. They have just cleaned it up, and integrated it with their own work. There are new window and door openings, but you can't really tell which is old and which is new. The result is that on the exterior, you are not really aware of just how much the building has been changed - it has become all Herzog and de Meuron. Yet despite its architectural Calvinism, Bankside has seduced everyone who has seen it. The light, the river, the space make an immediate impression.

Now that it's finished, complete with the little tip of light on top of the chimney, it's hard to see how else it could have been done. Of course, the Tate should divide its collection between modern and British. Of course, it should move its modern collection away from Millbank. And, of course, it should be in Bankside. It wasn't always that way. The Millennium Commissioners who put up much of the cash needed careful persuasion. At least one of the them, Simon Jenkins, was far from convinced that the old power station would make a plausible art gallery. Better turn it over to nineteenth-century machinery rather than give it to the Tate, 'a place dedicated to presenting dirty underpants as art', he argued while pressing the merits of the Dome.

But the positive response to Bankside will open the doors to a new generation of architects, one to whom the old arguments about the architectural avant garde versus traditional virtues of the Prince of Wales variety will seem like an antediluvian irrelevance.

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